Cushion for a respiratory mask assembly

ABSTRACT

A respiratory mask assembly for delivering breathable gas to a patient includes a frame and a cushion. The cushion has a non-face contacting portion structured to be connected to the frame, a face-contacting portion structured to engage the patient&#39;s face, and an intermediate portion that interconnects the non-face contacting portion and the face-contacting portion. The intermediate portion includes a gusset portion that applies a first component of force to the patient&#39;s face through the face-contacting portion. A spring structure is coupled with the face-contacting portion of the cushion. The spring structure applies a second component of force to the patient&#39;s face through the face-contacting portion. The first and second components of force applied by the gusset portion and spring structure, respectively, determine a contact force of the cushion applied to the patient&#39;s face through the face-contacting portion. The intermediate portion may also include an elastic cuff portion. Further, in the case of an oral mask, the sealing section may include a portion that is designed to promote a better seal in the chin region of the mask.

CROSS REFERENCE TO PRIORITY APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/251,000, filed Apr. 11, 2014, now allowed, which is a continuation ofU.S. patent application Ser. No. 13/067,211, filed May 17, 2011, nowU.S. Pat. No. 8,733,358, which is a continuation of U.S. patentapplication Ser. No. 12/382,517, filed Mar. 18, 2009, now U.S. Pat. No.7,958,893, which is a divisional of U.S. patent application Ser. No.10/655,622, filed Sep. 5, 2003, now U.S. Pat. No. 7,523,754, whichclaims the benefit of U.S. Provisional Application No. 60/424,686, filedNov. 8, 2002, U.S. Provisional Application No. 60/483,622, filed Jul. 1,2003, and is a Continuation-In-Part of U.S. Non-Provisional applicationSer. No. 10/235,846, filed Sep. 6, 2002, now U.S. Pat. No. 6,823,869,which in turn claims priority to U.S. Provisional Application No.60/317,486, filed Sep. 7, 2001 and U.S. Provisional Application No.60/342,854, filed Dec. 28, 2001. Each of the above identifiedapplications is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a cushion for a respiratory maskassembly used for providing ventilatory support, e.g., for treatment ofSleep Disordered Breathing (SDB) with Non-invasive Positive PressureVentilation (NPPV).

BACKGROUND OF THE INVENTION

The use of NPPV for treatment of SDB such as Obstructive Sleep Apnea(OSA) was pioneered by Sullivan (see U.S. Pat. No. 4,944,310). Apparatusfor the treatment of SDB involves a blower which delivers a supply ofair at positive pressure to a patient interface via a conduit. Thepatient interface may take several forms, such as a nasal mask assemblyand a nasal and mouth mask assembly. Patients typically wear a maskassembly while sleeping to receive the NPPV therapy.

Mask assemblies typically comprise a rigid shell or frame and a softface-contacting cushion. The cushion spaces the frame away from thepatient's face. The frame and cushion define a cavity which receives thenose or nose and mouth. The frame and cushion are held in position onthe patient's face by a headgear assembly. The headgear assemblytypically comprises an arrangement of straps which pass along both sidesof the patient's face to the back or crown of the patient's head.

U.S. Pat. No. 5,243,971 (Sullivan and Bruderer) describes a nasal maskassembly for Continuous Positive Airway Pressure (CPAP) having aballooning/molding seal that conforms with the patient's nose and facialcontours. The mask assembly has a face-contacting portion mounted to ashell which is sized and shaped to overfit the nose region of thepatient. The face-contacting portion is in the form of a distendablemembrane which is molded from an elastic plastics material. Thedistendable membrane and the shell together define a chamber.Pressurized gas admitted to the chamber causes the membrane to distendoutwardly from the patient's face. The contents of this patent arehereby incorporated by reference.

U.S. Pat. No. 6,112,746 (Kwok et al.) describes a nasal mask assemblyand a mask cushion therefor. The cushion comprises a substantiallytriangularly shaped frame from which extends a membrane. The frame has ascalloped edge by which the cushion is affixed to a mask body. Themembrane has an aperture into which the patient's nose is received. Themembrane is spaced away from the rim of the frame, and its outer surfaceis of substantially the same shape as the rim. The contents of thispatent are hereby incorporated by reference.

In a traditional mask assembly including a cushion, a seal is formedbetween the cushion and the face of a patient as the result of a contactforce which acts along a contact line of the cushion. The contact forcetypically is a function of tension in the headgear straps which actsthrough the frame of the mask assembly, the walls of the cushion and theseal-forming portion of the cushion. In a traditional mask assembly, theframe defines a cavity or volute adapted to receive at least a portionof the nose, with the cushion forming a perimeter of the cavity. Thus,in use, the portion of the patient's face within the cavity is exposedto air or breathable gas at positive pressure and hence receives a forceas the result of that positive pressure.

PCT Patent Application AU01/00746, published as WO 01/97893 (Frater etal.), describes a mask assembly for delivering air to a patient thatincludes a suspension mechanism to allow relative movement between aface-contacting cushion and a mask shell. The suspension mechanism alsoprovides a predetermined force to the cushion that is a function of maskpressure, displacement of the cushion, or both. The contents of thispatent are hereby incorporated by reference.

U.S. Pat. No. 5,074,297 (Venegas) describes a respiratory mask assemblyfor use with intermittent positive pressure breathing treatment which issaid to facilitate the formation and automatic adjustment of the sealbetween a patient's face and a facial unit of the respiratory mask. Therespirator mask assembly comprises a facial unit, an expandable pistonadjacent the facial unit and a rigid support structure attached to oneend of the piston, and an attachment mechanism for securing the maskassembly to a patient. During the inspiration portion of the ventilationcycle a positive pressure is developed within the mask assembly, causingthe piston to expand. Because the attachment mechanism and the supportcooperate to resist significant expansion of the piston, a force isgenerated which presses the facial unit against the patient's face andmaintains an air tight seal. When pressure within the mask unitdecreases, the contact force on the facial unit is likewise decreasedand the seal is eliminated.

A common problem with prior art mask assemblies, such as the maskassemblies taught by U.S. Pat. Nos. 5,074,297, 5,243,971 and 6,112,746and PCT Patent Application AU01/00746, is patient comfort. Patients candevelop sores and red marks on their faces after several hours use of amask assembly. The nasal bridge area of the patient's face has beenidentified as being particularly sensitive.

Moreover, the face contacting portion may apply excessive pressure tothe wearer's face resulting in discomfort and possibly skin irritation.This can occur when the face contacting portion is distorted beyond itsnormal range of elasticity to conform to certain facial contours, thusrequiring the application of excessive forces to obtain a seal. In somecases, these excessive pressures and forces may cause the wearer's faceto distort to conform with the face contacting portion, which increaseswearer discomfort, facial soreness and ulceration.

Another common problem with prior art mask assemblies is buildup of CO₂in the mask cavity. Mask assemblies typically include a vent whichallows the continuous washout of exhaled gasses from the cavity. Onefactor affecting the washout of exhaled gases is the dead space withinthe mask cavity.

Another common problem with these masks is a broken or ineffective seal.for example, the mask may become dislodged if the wearer rolls over whensleeping, thereby creating a drag force on the gas supply line which istransmitted to the mask and breaking the seal between the mask andwearer. If a mask is used for the administration of Continuous PositiveAirway Pressure (CPAP) treatment for the condition obstructive sleepapnea, such a leak can result in a pressure supplied to the entrance ofthe wearer's airway that is below the therapeutic value. Thus, treatmentbecomes ineffective.

Another problem with mask assemblies which include a gusset section isvisual size, both perceived and actual.

Another problem with existing full face masks occurs when wearers movetheir jaws during treatment, which often happens. As a result, air leaksare created below the mouth from the mid-region extending to the regionat the sides or corners of the mouth.

It would be desirable to design a respiratory mask that can be securelysealed to a wearer's face without causing discomfort and minimize leak.

SUMMARY OF THE INVENTION

One aspect of the invention is directed towards a mask assembly having acushion that provides more comfort to the patient.

Another aspect of the invention is directed towards a mask assemblyhaving a cushion that controllably distributes facial contact pressurearound the patient's face.

Another aspect of the invention is directed towards a mask assemblyhaving a cushion that controllably distributes facial contact forcesaround a contact line on the patient's face.

Another aspect of the present invention provides a respiratory maskassembly for delivering breathable gas to a patient. The respiratorymask assembly according to one embodiment includes a frame and acushion. The cushion has a non-face contacting portion structured to beconnected to the frame, a face-contacting portion structured to engagethe patient's face, and an intermediate portion that interconnects thenon-face contacting portion and the face-contacting portion. Theintermediate portion includes a gusset portion that applies a firstcomponent of force to the patient's face through the face-contactingportion. A spring structure is coupled with the face-contacting portionof the cushion. The spring structure applies a second component of forceto the patient's face through the face-contacting portion. The first andsecond components of force applied by the gusset portion and springstructure, respectively, determine a contact force of the cushionapplied to the patient's face through the face-contacting portion.

Another aspect of the invention is directed towards a mask assemblyhaving a curvature which follows the line of the patient's face.

Another aspect of the invention is directed towards a mask assemblyhaving a gusset portion which has minimal impingement of a patient'svision.

Another aspect of the invention is directed towards a mask assemblyhaving a cushion with a gusset portion which has a low profile.

Another aspect of the invention is directed towards a mask assemblyhaving a gusset portion which seals at a low pressure and which iscomfortable at high pressures.

Another aspect of the invention is directed towards a mask assemblyhaving a cushion with gusset portion which provides stop structures toregulate pressure distribution.

Another aspect of the invention is directed towards a mask assemblyhaving a gusset portion providing additional footprint area and a springsection with a spring constant constructed so that the forces on theface from the cushion are a function of the additional footprint area,the mask pressure and the spring constant of the spring section.

Another aspect of the invention is to provide an elastic cuff to thecushion. The elastic cuff may have a modulus of elasticity which isgreater than a modulus of elasticity of the remaining portions of thecushion, such that it may vary more easily deform or stretch in responseto localized pressure and/or force changes between the mask and thewearer's face, thereby avoiding a compromise in the seal during movementof the patient. The elastic cuff may be formed in one piece with thecushion, along an intermediate portion of the cushion between thecontacting and non-contacting portions of the cushion. The elastic cuffmay also be formed separate from the cushion and assembled to thecontacting and/or non-contacting portions of the cushion.

A further aspect of embodiments of the invention provides a full facemask with a cushion that forms a stable and reliable seal with awearer's face.

An additional aspect of embodiments of the invention provides a fullface mask that effectively seals the region directly below and/or to thesides of the lower lip.

A further aspect of embodiments of the invention provides a full facemask that offers effective sealing at relatively high pressures.

Another aspect of embodiments of the invention provides a full face maskthat abuts the more stable bony regions of a wearer's face.

A further aspect of embodiments of the invention provides a full facemask that follows the natural contour of the face's bony structure belowthe mouth.

In one example, a full face respiratory mask comprises a frame includinga breathable gas port and cushion. The frame defines an inner chamberthat receives a wearer's nasal region and mouth. The cushion includes aflange connected to the frame, an inner rim defining an opening to theinner chamber of the frame, and a sealing portion disposed between theflange and the inner rim that contacts the wearer's face. The sealingportion includes a nasal seal section that spans a wearer's face abovethe wearer's nares, side seal sections extending from each side of thenasal seal section on both sides of the wearer's mouth, and a chin sealsection that extends between the side sections. The chin seal section isupwardly curved in an arch to follow the chin's bony contour.

In another example, a cushion for use in a full face respiratory mask,comprises a flange for connection to a mask frame, an inner rim definingan opening for surrounding the wearer's nares and mouth, and a sealingportion disposed between the flange and the inner rim that contacts thewearer's face. The sealing portion includes a nasal seal section thatspans a wearer's face above the wearer's nares, side seal sectionsextending from each side of the nasal seal section on both sides of thewearer's mouth, and a chin seal section that extends between the sidesections, wherein the chin seal section is upwardly curved in an arch tofollow the chin's bony contour.

Principles of these examples may be applied to any type of cushion foruse on a respiratory mask, including but not limited to siliconeelastomer, gel, foam or any combination thereof.

Principles of these examples may be applied to any type of respiratorymask, including CPAP systems or non-positive ventilation masks, such asrespirators.

Other aspects, features and advantages of this invention will becomeapparent from the following detailed description when taken inconjunction with the accompanying drawings, which are a part of thisdisclosure and which illustrate, by way of example, principles of thisinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings facilitate an understanding of the variousembodiments of this invention. In such drawings:

FIG. 1 is a front perspective view illustrating a mask assembly having acushion constructed in accordance with an embodiment of the invention;

FIG. 1B is a perspective view similar to FIG. 1;

FIG. 1C is a perspective view similar to FIG. 1, but taken from anotherangle;

FIG. 2 is a rear perspective view of the mask assembly shown in FIG. 1;

FIG. 2B is a perspective view similar to FIG. 2;

FIG. 3 is a rear view of the mask assembly shown in FIG. 1;

FIG. 3B is a perspective view similar to FIG. 3;

FIG. 4 is a side view of the mask assembly shown in FIG. 1;

FIG. 4B is a perspective view similar to FIG. 4;

FIG. 5 is a bottom view of the mask assembly shown in FIG. 1;

FIG. 5B is a top view of the mask assembly shown in FIG. 1;

FIG. 6 is a cross-sectional view of the cushion shown in FIG. 1;

FIG. 6B is a cross-sectional view of the cushion shown in FIG. 1 inaccordance with an alternative embodiment of the invention;

FIG. 6C is a perspective view similar to FIG. 6;

FIG. 7 is a side view of the cushion shown in FIG. 1;

FIG. 7B is a perspective view similar to FIG. 7;

FIG. 8 is a perspective view of the cushion shown in FIG. 1;

FIG. 8B is a perspective view similar to FIG. 8;

FIG. 9 is a bottom view of the cushion shown in FIG. 1;

FIG. 9B is a perspective view similar to FIG. 9;

FIG. 10 is a front view of a gusset portion of the cushion shown in FIG.1 superimposed on a patient's face;

FIG. 10B is a front view of a gusset portion of the cushion shown inFIG. 1 superimposed on a patient's face, the contact line of themembrane on the patient's face shown in dashed lines;

FIG. 11 is a front view of a gusset portion of the cushion shown in FIG.1;

FIG. 11B is a perspective view similar to FIG. 11;

FIG. 12 is a front view illustrating different embodiments of a gussetportion of the cushion shown in FIG. 1;

FIG. 12B is a front view similar to FIG. 12 illustrating differentembodiments of a gusset portion of the cushion shown in FIG. 1;

FIG. 12C is a front view similar to FIG. 12 illustrating a differentembodiment of a gusset portion of the cushion shown in FIG. 1;

FIGS. 13A-13C are cross-sectional views illustrating differentembodiments of a spring structure within a gusset portion of the cushionshown in FIG. 1;

FIG. 14 is a partial top view illustrating an embodiment of the cushionshown in FIG. 1;

FIG. 15 is a cross-section taken along line 15-15 of FIG. 14;

FIG. 16 is a cross-section taken along line 16-16 of FIG. 14;

FIG. 17 is a cross-section taken along line 17-17 of FIG. 14;

FIG. 18 is a cross-section taken along line 18-18 of FIG. 14;

FIG. 19 is a cross-section taken along line 19-19 of FIG. 14;

FIG. 20 is a cross-section taken along line 20-20 of FIG. 14;

FIG. 21 is a cross-section taken along line 21-21 of FIG. 14;

FIG. 22 is a cross-section taken along line 22-22 of FIG. 14;

FIG. 23 is a partial top view illustrating an embodiment of the cushionshown in FIG. 1;

FIG. 24 is a cross-section taken along line 24-24 of FIG. 23;

FIG. 25 is a cross-section taken along line 25-25 of FIG. 23;

FIG. 26 is a cross-section taken along line 26-26 of FIG. 23;

FIG. 27 is a cross-section taken along line 27-27 of FIG. 23;

FIG. 28 is a cross-section taken along line 28-28 of FIG. 23;

FIG. 29 is a cross-section taken along line 29-29 of FIG. 23;

FIG. 30 is a cross-section taken along line 30-30 of FIG. 23;

FIG. 31 is a cross-section taken along line 31-31 of FIG. 23;

FIG. 32 is a cross-section taken along line 32-32 of FIG. 23;

FIG. 33 is a cross-section taken along line 33-33 of FIG. 23;

FIG. 34 is a front perspective view of an embodiment of the cushionshown in FIG. 1;

FIG. 35 is a rear perspective view of the cushion shown in FIG. 34;

FIG. 36 is a top view of the cushion shown in FIG. 34;

FIG. 37 is a side view of the cushion shown in FIG. 34;

FIG. 38 is a cross-section taken along line 38-38 of FIG. 36;

FIG. 39 is a cross-section taken along line 39-39 of FIG. 36;

FIG. 40 is a cross-section taken along line 40-40 of FIG. 36;

FIG. 41 is a cross-section taken along line 41-41 of FIG. 40;

FIG. 42 is an enlarged cross-sectional view of FIG. 38;

FIG. 43 is a graph that illustrates the relation between mask pressureand contact force on the patient's face for a mask with at least agusset portion wherein the gusset portion is held at a fixed extension;

FIG. 44 is a graph that illustrates the effect a spring structure has onthe total force applied to the patient's face at a constant maskpressure;

FIG. 45 is a cross-sectional view of another embodiment of the inventionincluding an elastic nasal cuff.

FIG. 46 is a force versus displacement graph for ResMed's Activa™ mask;

FIG. 47 is a force versus displacement graph for a prior art mask;

FIG. 47A is a cross-sectional view of a mask according to the prior art;

FIG. 48 is a force versus displacement graph for an embodiment of thepresent invention;

FIG. 49 is a cross-sectional view of yet another nasal cuff embodimentof the present invention;

FIG. 50 is a front perspective view of a full face mask positioned on awearer in accordance with a preferred embodiment of the invention;

FIG. 51 is a front perspective view of the mask frame and cushion inaccordance with a preferred embodiment of the invention;

FIG. 52 is a rear perspective view of the cushion in accordance with apreferred embodiment of the invention;

FIG. 53 is a front view of the cushion of FIG. 52;

FIG. 54 is a rear view (from the wearer's side) of the cushion of FIG.52;

FIG. 55 is a bottom view of the cushion of FIG. 52; and

FIG. 56 is a cross section side perspective view of the cushion takenalong line 56-56 of FIG. 54.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

FIGS. 1-5B show a respiratory mask assembly 10 that includes a frame 12and a cushion 14 that may be permanently or removably connected to theframe 12. A forehead support 16 is movably mounted to an upper portionof the frame 12. A headgear assembly (not shown) can be removablyattached to the frame 12 to maintain the frame 12 and cushion 14 in adesired adjusted position on the patient's face. For example, theheadgear assembly may include a pair of upper and lower straps with theupper straps removably connected to clip structures 18 provided on theforehead support 16 and the lower straps removably connected to clipstructures 20 provided on the frame 12. However, the headgear assemblyand frame 12 may be removably attached to one another in any suitablemanner.

In the illustrated embodiment, the mask assembly 10 is a nasal maskstructured to deliver breathable gas to a patient's nose. However, themask assembly 10 may be nasal and mouth mask or the mask assembly may bea full-face mask.

A swivel elbow assembly 22 is removably attached to a front portion ofthe frame 12. The elbow assembly 22 is structured to be connected to aconduit that is connected to a pressurized supply. The pressurizedsupply supplies pressurized breathable gas through the conduit and elbowassembly 22 and into the cushion 14 for breathing by the patient.

As shown in FIGS. 1-9B, the cushion 14 includes a non-face-contactingportion 24 (FIGS. 6 and 6C) structured to be connected to the frame 12,a face-contacting portion 26 structured to engage a patient's face, andan intermediate portion 28 that interconnects the non-face contactingportion 24 and the face-contacting portion 26. A seal-forming portion 68(see FIG. 10B) of the cushion 14 is designed to seal on the patient'sface. The cushion 14 achieves a seal by applying a contact force alongthe seal-forming portion 68 as will be described in further detailbelow. In one form, the seal-forming portion 68 is a strip with an area.For example, the strip 68 that contacts the patient's face could be thatarea between the dashed sets of lines in FIG. 10B. The contact forceapplied to sensitive regions on the patient's face can be minimized.Some portions of the patient's face require special attention to achievea balance of comfort and seal.

In the illustrated embodiment, the non-face-contacting portion 24 of thecushion 14 is removably attached to the frame 12. For example, as shownin FIGS. 3, 3B, 6, 6C, and 15, the non-face-contacting portion 24includes a shoulder 30 and a flange 32. A cushion clip 34 (see FIGS. 2,2B, 3, and 3B) is detachably engaged with the frame 12 such that theshoulder 30 is positioned between the clip 34 and the frame 12 to attachthe cushion 14 to the frame 12, e.g., see co-owned and co-pending U.S.patent application Ser. No. 10/235,846, filed on Sep. 6, 2002,incorporated herein by reference in its entirety. Further, the flange 32is positioned to provide a seal. Alternatively, the non-face-contactingportion 24 of the cushion 14 may be removably attached to the frame 12with straps, a friction or interference fit, and/or a tongue-and-groovearrangement, as is known in the art. However, the non-face-contactingportion 24 of the cushion 14 may be permanently attached to the frame 12with glue and/or mechanical fastening means, for example.

As shown in FIGS. 6, 6C, and 14-33, a preferred face-contacting portion26 of the cushion 14 includes a side wall 36, a rim 38 extending awayfrom the side wall 36, and a membrane 40 provided to substantiallysurround the rim 38, e.g., see U.S. Pat. No. 6,112,746 of Kwok et al.and U.S. Provisional Application No. 60/402,509, filed on Aug. 12, 2002,incorporated herein by reference in its entirety. The rim 38 and sidewall 36 provide a support structure for the face-contacting portion 26and the membrane 40 provides a sealing structure for the face-contactingportion 26.

The membrane 40 provides a large effective rolled over section (largeradius) to allow some degree of movement or rotation of the maskassembly 10 relative to the patient's face, and prevents the membranedistal edge from irritating the patient's face. Further, the membrane 40extends further than the edge of the rim 38 to prevent the rim 38 frombeing a source of irritation.

The rim 38 has a curved shape that curves inwardly into the nasal cavityof the cushion 14. While it is preferable that the membrane 40 bethinner than the rim 38, they could have the same thicknesses.

The inside surface of the membrane 40 is spaced from the outside surfaceof the rim 38 so as to form a compliant seal with the patient. Bycompliant seal, it is meant that the membrane 40 can accommodate smallvariations in the shape of a patient's facial/nasal features withoutundue force, and can account for small movement of the mask relative tothe patient during use, while maintaining an effective seal. The spacingbetween the rim 38 and membrane 40 may vary in different regions of thepatient's face.

As shown in FIGS. 2, 2B, and 10-11B, the face-contacting portion 26 ofthe cushion 14 preferably has a generally triangular shape and isstructured to contact the nasal bridge, cheek, and lip regions of thepatient. However, the face-contacting portion 26 may have any othersuitable shape, e.g., a generally trapezoidal shape. In the illustratedembodiment, the cushion 14 includes a pair of cheek regions 44 toprovide a seal in the crease between the cheeks and the sides of thenose, a lip region 46 to provide a seal below the nose and above theupper lip of the patient, and a nasal bridge region 42. The nasal bridgeregion 42 spans across the bridge and sloping sides of the bridge thatintersect with the nasal crease formed between the cheeks and the sidesof the nose. The transition between the lip region 46 and each cheekregion 44 is where the cushion 14 begins to turn around the bottom ofthe nose towards the side of the nose. The transition between the nasalbridge region 42 and each cheek region 44 is where each cheek region 44diverges upwardly towards the bridge of the nose. In other words, thenasal bridge region 42 starts where the cheek region 44 begins to angleupwardly. As shown in FIG. 40, the membrane 40 may include a preformed,contoured notch 48 in the nasal bridge region 42 to match generally thetypical contours of the nasal bridge region of the patient.

The cushion 14, including the gusset portion 50, is curved to generallyfollow the curvature of the face. See FIGS. 4-5B and 7-9B. Theadvantages of the above structure include a reduced height profile,increased stability, better fit to the patient's face and a reducedvisual impact. Other advantages include a reduced height at sides of theframe 12 and headgear clip section which might otherwise protrude fromthe mask frame, decreased weight and volume of silicone, decreaseddeadspace and stiffened gusset portion which holds its shape better.

In the illustrated embodiment, the membrane 40 is structured to contactan upper portion of the nasal bridge region of the patient. However, themembrane 40 may contact a lower portion of the nasal bridge region. Forexample, see U.S. Provisional Application No. 60/402,509, filed on Aug.12, 2002, the contents of which are hereby incorporated by reference.

In the illustrated embodiment, the face-contacting portion 26 of thecushion 14 has a double-walled construction, e.g., one membrane 40 andone rim 38. However, the cushion 14 may have a single walled, triplewalled or more walled construction. For example, a cushion with acombined membrane and rim could be provided, e.g., a single walledconstruction. Conversely, the support function of the rim could beaccomplished with two or more support rims to support a single membrane,or two or more membranes could be provided over a single rim. In anotheralternative, the support function of the rim and the sealing function ofthe membrane could be split into two different members, which may bemade of different materials, for example either being made of a foam. Inanother embodiment, a gel membrane may be used.

The intermediate portion 28 of the cushion 14 includes a gusset portion50 that extends radially outwardly with respect to thenon-face-contacting and face-contacting portions 24, 26. The gussetportion 50 allows the face-contacting portion 26 to move relativethereto. Furthermore, the gusset portion 50 has a larger footprint areathan the face-contacting portion 26 (e.g., FIG. 10 shows the gussetportion 50 superimposed on a patient's face to illustrate the additionalarea provided by the gusset portion 50). The additional footprint areaof the gusset portion 50 provides a contact force on the patient's faceacting on the sealing strip 68 (FIG. 10B) through the membrane 40, whichincreases the sealing efficiency of the cushion 14, as will be furtherdiscussed.

As shown in FIGS. 6, 6C, and 15, the gusset portion 50 extends outwardlyfrom the side wall 36 of the face-contacting portion 26 and curves backinwardly into the flange 32 of the non-face-contacting portion 24.Specifically, the gusset portion 50 includes a first side wall 52extending outwardly from the side wall 36 of the face-contacting portion26, a second side wall 54 extending outwardly from the flange 32 of thenon-face-contacting portion 24, and an arcuate wall 56 thatinterconnects the first and second side walls 52, 54. The walls 52, 54,and 56 of the gusset portion 50 defines a space 57 therebetween. Thus,the gusset portion 50 is curved as viewed from above to follow thecontour of the patient's face. As shown in FIG. 39, for example, thegusset portion has a radius of curvature in the range of 80-120 mm,preferably in the range of 95-105 mm.

The gusset portion 50 has an inner edge 58 and an outer edge 60. Theinner edge 58 corresponds to an outer edge of the side wall 36 and theouter edge 60 corresponds to an apex of the arcuate wall 56 of thegusset portion 50. A perpendicular distance d is defined between theinner and outer edges 58, 60, as shown in FIGS. 6 and 10. The distance dmay be varied to vary the pressure applied by the cushion 14 on thepatient's face. The distance d₂ is defined as shown in FIG. 10B to bethe perpendicular distance between the outer edge 60 and a cushioncontact line 61 on the face. The contact line 61 is the outer perimeterof the seal-forming portion 68, that is, the sealing strip of thecushion 14. The additional area between the contact line 61 and theouter edge 60 leads to an additional force on the membrane 40. Thecontact force on the patient's face is proportional to the pressure inthe mask cavity and the footprint area of the gusset portion 50. Thus,the additional area of the gusset portion 50 may be varied, e.g., byvarying the distance d, to vary the contact force applied to thepatient's face.

An aspect of the invention is that the contact force is controllablydistributed around the patient's face. The pressures and forces shouldbe distributed while maintaining the cushion's seal. It is desirable toavoid localized pressure points along sensitive regions of the patient'sface. For example, localized points of contact force should be avoidedin the nasal bridge region to increase comfort to the patient.

Another aspect of the invention is that not only can the contact forcebe redistributed while maintaining the cushion seal, but also thepatient's field of view can be optimized by reshaping the gusset areaaround the eyes. For example, as shown in FIG. 12C, the gusset portion50 has cutaway portions 51 around the eyes to improve the patient'sfield of view.

Since the contact force applied to the patient's face is proportional tothe footprint area of the gusset portion 50, it is possible to vary theforce applied to different regions of the patient's face by varying thedistance d in different regions of the gusset portion 50. For example,FIG. 12 shows a gusset portion 50 with two possible outer edges. A firstouter edge 60, shown in a solid line, has an approximately constantdistance d between the inner and outer edges 58, 60. In contrast, thesecond outer edge 260, shown in dashed lines, has a smaller distance d′in the lip and nasal bridge regions in comparison to the cheek regions.

The gusset portion 50 can be provided in only selected regions of theface, and not others. It need not be provided along the entire perimeterof the cushion. For example, the gusset portion 50 could be providedalong only the lip portion.

Thus, the gusset portion 50 with the outer edge 260 in dashed lines hasa smaller contact force applied to the nasal bridge and lip regions ofthe patient's face than the gusset portion 50 with the outer edge 60 ina solid line. In this way, the contact force applied to the patient'sface can be redistributed away from more sensitive areas of thepatient's face, e.g., nasal bridge and lip region, and applied to lesssensitive areas of the patient's face, e.g., cheek regions. Since thenasal bridge region of the patient's face is particularly sensitive, agusset portion 50 with a reduced area in the nasal bridge region 42should be more comfortable for the patient. However, the distance d canbe tailored for any region of the gusset portion 50 to tailor the forceapplied to any region of the patient's face for maximum comfort. Thiscan be done on a customized basis to get both an ideal force and acustomized area around the cushion.

FIG. 12B shows another embodiment of a gusset portion 50 with twopossible outer edges. A first outer edge 60, shown in a solid line, hasa smaller distance between the outer edge 260 and an inner edge (notshown) in the lip and nasal bridge regions in comparison to the cheekregions. In contrast, the second outer edge 260, shown in dashed lines,has an approximately constant distance between the outer edge 60 and aninner edge.

The contact force applied to the contact line on the patient's face canbe further tailored by adjusting a thickness of the arcuate wall 56 ofthe gusset portion, as shown in FIGS. 6, 6C, and 13A-C. The arcuate wall56 acts as a spring structure to provide a component of the contactforce on the patient's face through the membrane 40. The arcuate wall56′ may have a uniform wall thickness or a thin cross-section as shownin FIG. 13A or the arcuate wall 56″ may have a thicker cross-section asshown in FIG. 13B, with the thinner arcuate wall 56′ providing a smallercomponent of force than the thicker arcuate wall 56″. The cross-sectionof the arcuate wall 56, 56′, 56″, 56′″ may vary around the perimeter ofthe gusset portion 50. For example, a gusset portion may have a thinwalled arcuate wall in the patient's nasal bridge region, but a thickerwalled arcuate wall in the patient's cheek region. Moreover, the arcuatewall may be varied in conjunction with the varying distance d, forexample, by reducing the distance d but increasing the thickness of thearcuate wall.

Alternatively, the whole gusset portion 50 may be tapered, not just thearcuate wall.

The contact force applied to the contact line on the patient's face canbe further tailored by providing internal stop structures 59 as shown inFIG. 13C at the gusset portion 50. The size, shape and geometry of thesestop structures 59 can be arranged to vary stiffness in differentsections of the gusset portion 50. For example, less stiff sections atnasal bridge region, stiffer sections at cheek region, to provide therequired comfort and seal level.

In another form, the contact force applied to the contact line on thepatient's face can be tailored by inserting a spring (e.g. a steelspring) in the gusset portion 50. The spring has a spring constant thatis designed to allow adjustment of the component of force applied by thespring.

In these ways, the contact force on the contact line of the face is notsolely a function of mask pressure, but can also, for example, be afunction of the spring element within the gusset portion 50. Thisimproves low pressure stability, reduces the sealing force at highpressure, and reduces the visual impact a large gusset portion mightotherwise have.

In the illustrated embodiment, the gusset portion 50 as well as thenon-face-contacting and face-contacting portions 24, 26 of the cushion14 have a generally triangular shape. However, the gusset portion 50 andnon-face-contacting and face-contacting portions 24, 26 of the cushion14 may have any suitable shape, e.g., non-triangular shape. Further, theshape of the gusset portion 50 and non-face-contacting andface-contacting portions 24, 26 may be similar to one another or may bedifferent from one another, e.g., the gusset portion has a triangularshape and the face-contacting and non-face-contacting portions have agenerally trapezoidal shape.

The cushion 14 is constructed from a soft, flexible skin-compatiblematerial such as silicone. The cushion 14 may be formed, for example, ina one shot injection molding process as is known in the art. However,the cushion 14 may be formed with any suitable material and may beformed by any suitable process. For example, while face contactingportion 26 of cushion 14 may have a softer grade material, the gussetportion may have a harder grade material to provide stiffness as aspring element. The non-face contacting portion 24 may have a stiffergrade material so a direct assembly to frame without a cushion clip maybe possible.

The cushion 14 provides improved seal stability and comfort over priorart cushions. Specifically, the curvature of the cushion 14 improvesstability of the mask assembly generally and the gusset portion improvesstability of seal. Changing the distances d and d₂ of the gusset portionin different regions of the patient's face improves patient comfortlevel.

FIGS. 14-33 show various cross-sections of the cushion 14. The variouscross-sections illustrate the various distances between the rim and themembrane in different regions of the patient's face. Moreover, thevarious cross-sections illustrate the various structural configurationsand distances d of the gusset portion 50 in different regions of thepatient's face.

FIGS. 34-42 shows further structural details and various dimensions inone embodiment of the cushion 14. For example, the cushion 14 has alength in the range of 42-62 mm, preferably 52 mm, a height in the rangeof 90-110, preferably 100.5 mm, and a width in the range of 95-115 mm,preferably 103.2 mm. In an embodiment of the cushion 14, the dimensionsillustrated in FIGS. 34-42 may vary ±62 or 100%.

FIG. 6B shows an alternative embodiment of the invention which includesa reinforcing ring 64 between the gusset portion 50 and face-contactingportion 26 of the cushion 14. In one form, the ring 64 is constructedfrom a thickened bead of silicone and is molded with the cushion 14. Thering 64 acts as a stiffening hoop reducing the tendency of the cushion14 to expand at that point when under pressure. In another form, thering 64 is made from polycarbonate and is overmolded or push-fit.

The face-contacting portion 26 of the cushion 14 has a surface which maybe described by a function of at least one parameter, p, varying from 0to 360 degrees representing angular position. With respect to the nose,the 0 degree position may be defined to be mid-nasal bridge and thenasal septum will occur at 180 degrees. FIGS. 15-22 and 24-33 depict arange of cross-sections cut at different angular positions, and hencedifferent values of the parameter, p.

An advantage of the mask assembly 10 is that the contact force actingthrough the contact strip can be tailored to provide an acceptable sealat low mask pressures while not being too high at high mask pressures.For example, in a mask assembly having a gusset portion with no springstructure, the contact force might be too low at low mask pressures toprovide a seal, forcing designers to increase the gusset area. Thisadditional gusset area in turn would lead to an excessively high contactforce at high mask pressures. The combination of a spring structure witha gusset portion means that at low mask pressures, the contact force maybe provided by the spring structure, with the gusset portion makinglittle additional contribution. At high mask pressures, the contactforce provided by the gusset portion may be much greater than thatprovided by the spring structure. Thus, the mask assembly 10 provides ameans to tailor the contact forces of a mask system over a range ofpressures.

In another form of the invention, the extensibility of the headgear ischangeable. For example, relatively inextensible headgear might be usedfor low mask pressures, while more extensible headgear may be used forhigh mask pressures, such as around 20 cm H₂O. In one form, this isachieved by having duplicate straps within the headgear, one extensible,the other, relatively inextensible. At low pressures, both straps areused, the net effect being that the headgear is relatively inextensible.At high pressures, the inextensible strap is disengaged, with the resultthat the headgear is relatively extensible overall.

FIG. 43 illustrates the contact force on the patient's face for a maskwith at least a gusset portion wherein the gusset portion is held at afixed extension, e.g., expansion. The x-axis is the pressure inside themask. The y-axis is the contact force on the patient's face. A zone ofcomfort and seal Z is defined by: (a) a range of typical operatingpressures from 4 to 20 cm H₂O; (b) a minimum contact force that isrequired to maintain a seal on a patient's face, the minimum contactforce defined as an increasing function of the pressure inside the mask;and (c) a maximum comfortable contact force.

In accordance with an embodiment of the invention, the cushion isdesigned to include a gusset portion and spring structure such that thecontact force applied by the cushion is maintained within the zone ofcomfort and seal Z.

FIG. 43 shows three lines for three hypothetical cushions with at leasta gusset portion. In general, at a first approximation, contact forceincreases linearly with mask pressure as the result of the additionalfootprint area provided by the gusset portion.

A first line L1 represents a cushion with a gusset portion which has anadditional footprint area of A1 and which does not include a springstructure. As illustrated, the contact force is below the minimumcontact force required to make a seal for mask pressures below about 7cm H₂O. Thus, the cushion represented by line L1 falls outside the zoneof comfort and seal Z. For higher pressures (e.g., mask pressures aboveabout 7 cm H₂O), the contact force from the gusset portion is sufficientto maintain a seal.

A second line L2 represents a cushion according to one embodiment of theinvention with a gusset portion which has an additional footprint areaof A1 and includes a spring structure. The effect of the springstructure is to provide an additional contact force at low maskpressures when the effect of the gusset portion is insufficient toprovide the minimum sealing force. As a result, the cushion maintains aseal through the range of operating pressures. Moreover, the cushionrepresented by line L2 falls within the zone of comfort and seal Zthroughout the range of operating pressures.

A third line L3 represents a cushion with a gusset portion which has anadditional footprint area of 2×A1 and does not include a springstructure. The extra footprint area (twice that of the cushionsrepresented by L1 and L2) results in the contact force of the cushionbeing sufficient to maintain a seal at a low mask pressure of 4 cm H₂O.However, for mask pressures above about 10 cm H₂O, the contact forceexceeds the maximum comfortable contact force. Thus, the cushionrepresented by line L3 falls outside the zone of comfort and seal Z.

Thus, by combining a gusset portion with a spring structure in acushion, a designer can tailor the contact force of the cushion suchthat it falls within the zone of comfort and seal Z throughout theworking range of pressure. The same principles may be applied fordifferent pressure ranges.

Further, the size of the zone Z may change (e.g., by changing themaximum comfortable contact force) depending on a particular region ofthe patient's face. For example, the maximum comfortable contact forcemay be reduced for a nasal bridge region of the face. As a result, thecushion can be tailored for that particular region such that it fallswithin the zone of comfort and seal Z throughout the range of operatingpressures.

FIG. 44 illustrates the effect a spring structure has on the total forceapplied to the patient's face at a constant mask pressure. F_(mask) isthe total force of the mask on a patient's face, as defined in WO01/97893 (Frater et al.). The inclusion of the gusset portion on themask allows the two sides of the cushion to travel relative to oneanother. When the extension or expansion of the gusset portion is 0 mm,the two sides of the cushion abut one another. When the extension of thegusset portion is 50 mm, the two sides of the cushion are 50 mm apart.The closer the two sides of the cushion are brought towards one another,the higher the value of F_(mask).

FIG. 44 shows four lines that represent four different cushions. A firstline L1 is for a cushion with a gusset portion with no spring structureand with an additional footprint area of A1. A second line L2 is for acushion according to one embodiment of the present invention with agusset portion, a spring structure, and an additional footprint area of62% of A1. A third line L3 is for a cushion with a gusset portionwithout a spring structure and with an additional footprint area of 85%of A1. A fourth line L4 is for a cushion with a gusset portion without aspring structure and with an additional footprint area of 62% of A1.

As illustrated, the addition of a spring structure to a cushion having agusset portion increases F_(mask) generally throughout the range ofgusset extensions. As a result, a cushion may be constructed with agusset portion having a smaller footprint area than would otherwise berequired to provide sufficient F_(mask) to maintain a seal.

Further, the effect of the spring on F_(mask) can be determined forvarious mask pressures so that the cushion can be tailored forparticular regions of the patient's face.

Elastic Cuff

FIGS. 45-49 show an alternative embodiment of the present inventionwhich may be used in conjunction with earlier or later describedembodiments. As shown in FIG. 45, a mask assembly 100 includes a maskframe 112, a cushion 114 and a strap 116, all of which can be assembledin a fashion which is similar to that described above in relation toother embodiments.

The frame includes an inlet 122 which is in communication with thesource of pressurized air or breathable gas. Preferably, the inlet isconnected to a swivel elbow which in turn is connected to an airdelivery tube.

The cushion 114 includes a non-contacting portion 124 which is providedto the mask frame 112, as described above. The cushion 114 furtherincludes a face contacting portion 126 and an intermediate portion 128which is between the non-contacting portion and the face contactingportion 126. The face contacting portion 126 includes a face-contactingseal portion 168 including a membrane 140 and a rim 138, as describedabove.

The intermediate portion 128 may be provided with at least one cuff 170that may be resiliently inflatable. The cuff 170 includes walls that canstretch as opposed to being simply flexible. As the straps 116 aretightened, membrane 140 and rim 138 are pushed onto the face. Thisaction causes a force to be applied to the membrane 140, the rim 138 andthe face-contacting portion 126, displacing the face contacting portion126 in the direction of the non-contacting portion 124. The displacementof the face contacting portion 126 and its associated force causes thecuff 170 to balloon outwards. The force is dependent on the degree ofstrap tightening and the stiffness (force-displacement relationship) ofthe cuff 170. Initial inflation of the cuff 170 can be achieved via avalve 175. The valve 175 can be in communication with the same sourcewhich provides pressurized air to the breathing chamber 171 of the maskassembly 100, or the source can be a separate pressurized sourceindependent of the source for providing pressurized breathable gas tothe breathing chamber 171. The elastic cuff 170 can be formed in asingle piece with the cushion 114. Alternatively, the elastic cuff 170may be formed separately from the cushion 114, and later attached, e.g.,using adhesives, mechanical fasteners, or the like, etc.

Current mask systems use inflatable cuffs that are relatively stiffbeing made from materials having a relatively high modulus ofelasticity. By contrast the cuffs 170 of the present embodiment aredesigned to have a relatively low stiffness. This is achieved, e.g., byproviding the cuffs 170 with walls that stretch under relatively lowforces. Walls with this characteristic typically are made from amaterial with a relatively low modulus of elasticity. For example, themodulus of elasticity of the material of the elastic cuff material, asdetermined by bench testing, is in the range of 0.15 MPa to 0.6 MPa. Thepreferred value for the modulus of elasticity is in the range of 0.25MPa to 0.45 MPa. In one example, the modulus of elasticity is about 0.35MPa. In comparison, the gusset portion described above may have amodulus of elasticity of 0.40 MPa to 0.80 MPa, and preferably themodulus of elasticity is about 0.60 MPa. The modulus of elasticity forboth the gusset and the elastic cuff 170 can be more or less than thatstated above or modified to give the appropriate stretch characteristicsin conjunction with the delivered mask pressure and headgeartension/strap displacement.

In the embodiments described above, for example in relation to FIG. 1, amask system and cushion provided with a gusset produces a number ofpositive attributes, for example, the ability to maintain cushion sealwith relative frame instability, less fine adjustment required of headgear straps to apply a cushion force towards the face to maintain aseal. A cushion provided with the elastic cuff 170 of FIG. 45 alsoexhibits similar results to the above embodiments. However, the elasticcuff forces are independent of the supply air from the flow generator.

Prior art masks use inflatable (verses elastic) cuffs or pneumatic sealsand/or seal rings. These inflatable cuffs are typically made from PVCthat has a relatively high modulus of elasticity causing them to berelatively stiff. Bench testing of this PVC material found that themodulus of elasticity was of the order of 5.2 MPa. Although they mayinclude some flexibility, it is not resiliently expandable like theelastic cuff 170 shown in FIG. 45. Examples of inflatable cuffs with arelatively high modulus of elasticity include U.S. Pat. No. 4,971,051 toToffolon and anesthesia masks available from King Systems.

FIGS. 46-48, respectively, are force-displacement (stiffness) graphsfor 1) the embodiment shown above with a gusset (ResMed's Activa™ mask);2) the Prior Art; and 3) the elastic cuff shown in FIG. 45. It should benoted that the horizontal axis in these graphs labeled ‘d’ representsthe dimension shown as ‘d’ in FIG. 45 (described above) and FIG. 47Awhich shows a prior art mask frame 300 with straps 310 and an inflatablecuff 320. As shown in FIG. 46, the flattened region according to theActiva™ mask gives a mask system with greater tolerance to strap tensionor mask instability while maintaining relatively constant force ofcushion seal to face. See the line between points X-X in FIG. 46.

In contrast, the graph of FIG. 47 shows that the prior art inflatablecuff being made of a material with a relatively higher modulus ofelasticity has a more linear force-displacement characteristic and isstiffer. Therefore slight changes in the mask or cushion relative to theface that result in small changes to the dimension will cause relativelylarge changes in the sealing force applied to the face. Therefore, thisprior art mask system cannot maintain a good seal over increaseddisplacement (due to instability). Strap tension is critical to maintainthe tolerable level of comfort.

Therefore, one aspect of this embodiment is to produce an elastic cufffrom a material with a relatively low modulus of elasticity, like thatof a stretchy balloon. The elastic cuff material has the ability tostretch under standard strap tension experienced in this application.

When the mask is not fitted, the inflatable cuff is not necessarilyunder pressure. When fitted correctly, the cuff is compressed as thestraps are tightened. Given the low modulus of elasticity of the elasticcuff material, the cuff is designed to stretch, billow, bloat and/orswell as the cuff elongates as shown in phantom in FIG. 45.

The force applied to the cushion seal could be fine tuned by modifyingthe stiffness of the cuff walls, e.g., increasing or decreasing themodulus of elasticity, or by pre-pressurizing the elastic cuff 170 via avalve that, in this example, would increase cushion seal forces when thecushion is displaced and/or fitted into position and the strapstensioned.

As shown in FIG. 48, the elastic cuff 170 is made from a material with alower modulus of elasticity that produces a similar flattened line tothat shown in FIG. 46. However, this graph is slightly angled ascompared to FIG. 46, but it is flatter than that shown in FIG. 47. Theideal is to have the angle flat in the middle such as shown in FIGS. 46and 48.

A stiffer cuff made from a material with a higher modulus of elasticitywould produce a greater rate of fall as compared to that shown in FIG.48. For prior art inflatable cuffs, the relatively very high stiffnessresults in a very large change in cushion seal force for very slightdisplacements that may lead to a loss of the seal of the face. Eventsthat may lead to slight displacement include, for example, nocturnalmovements that result in changes to strap tightness, human face fluidreduction, relaxation of the lower jaw, etc.

In a further embodiment, the elastic cuff 170 may be filled with anycompressible or non-compressible fluid, or some combination thereof. Thefluid could be, for example, air, flowable liquid, flowable orsemi-flowable gel. In the case of air, the cuff walls in tension causethe air inside the cuff to compress and forces the cushion seal outwardstowards the face; there is some compression of the air as it is a gas.In the case of liquid filled, all the force onto the cushion seal isacted on by the cuff wall tension alone without the influence ofcompressed gas also.

Change in behavior of the cushion is achieved by any of or combinationof modulus of elasticity, geometry/shape of the elastic cuff, materialchoice (for example the modulus of elasticity), and the initial mass offluid (before fitting).

The initial mass of fluid may be adjusted by a valve either manually orautomatically (incorporating external-internal control relative to cuffpressure and/or treatment CPAP pressure). In FIG. 45, it can be seenthat the elastic cuff is separate from the cushion assembly, i.e. thatportion of the cushion which seals against the face. It thereforeprovides minimal possible displacement, and only describes a flexiblepneumatic seal, not elastic or resilient.

In FIG. 45, the expandable/contractible elastic cuff 170 is incorporatedinto the cushion seal.

In another embodiment, the elastic cuff may be pressurized with a manualpump 180 to fine tune the initial mass of fluid in the elastic cuff 170.See, for example, FIG. 49.

Another embodiment may incorporate automatic cuff mass of fluid changethat can synchronize to delivered treatment pressure and/or react toleak or discomfort sensing.

Any elastic material that can be formed into a chamber or the elasticcuff 170 may be used. The use of a latex balloon is one material thatmay be used. Also, low durometer and/or low modulus of elasticitycharacteristic silicone rubbers may also be used, or a combinationthereof. The cuff may have rigid or semi-rigid detail to providestructural integrity.

The cuff 170 need not surround the entire perimeter. For example, it maybe excluded around the nasal bridge to modify received cushion sealforces. The elastic cuff 170 as disclosed herein may also beincorporated or used in conjunction with prior art mask systems, tocreate a new and improved product. For example, Respironics makes a“Profile Lite” gel cushion that could incorporate the elastic cuff 170either integrated or otherwise attached between the frame and sealinginterface. The elastic cuff may be filled with a compressible ornon-compressible fluid such as air or gel, or any combination thereof.

In another example, the elastic cuff 170 may be combined with aspects ofU.S. Pat. No. 4,971,051 to Toffolon. The elastic cuff could beincorporated as part of the cushion assembly to provide a force actionin the cushion seal and also independent movement/displacement of thecushion seal relative to the mask frame.

While a nasal mask has been described in the preferred embodiments, theprinciples of the invention can be applied to full-face masks or mouthmasks. Furthermore, the principles of the invention can be applied tonasal masks having a very small sealing region sealing near the nares.

“Boomerang” Seal

FIGS. 50-56 illustrate another embodiment of the invention which may beusable with earlier embodiments. FIG. 50 is a perspective view of thefull face respiratory mask 10 secured to a wearer's head. The mask 10includes a frame 12 that supports a cushion 14. The mask 10 is securedover the wearer's nasal area and mouth by head gear that includesfastening straps 16 that may be adjusted around the wearer's head.

The frame 12 is preferably saddle shaped, generally triangular ortrapezoidal to fit over the wearer's nose, or at least over the wearer'snares, and extends downwardly on each side of the mouth to the chin. Theframe 12 has a port 18 for connection to a breathable gas supply 20through a swivel elbow assembly 22. The gas supply 20 may be apressurized gas supply that supplies breathable gas to an inner chamberin the mask 10 that receives the wearer's nose and mouth.

The frame 12 also preferably includes a vent opening 24 through whichexpired gas is exhausted. Fasteners 26 are provided to secure the straps16 of the head gear and allow selective adjustment of the head gear. Inthis case, the fasteners 26 are slots formed in the frame 12 throughwhich the straps 16 are fed. Of course, any suitable fastener can beused. If desired, a forehead support may also be used, which wouldextend from the frame upward toward the forehead.

The frame 12 is shown alone with the cushion 14 in FIG. 51. As can beappreciated by those of ordinary skill in the art of respiratory masks,the cushion 14 may be secured to a flange 28 on the frame 12 by avariety of methods. The cushion 14 may be formed integral with theflange 28, it may be adhered to the flange 28, or it may be removablyclipped thereto. Other methods of attachment could also be usedincluding straps, friction or interference fit, or tongue and groove.

In FIG. 52, the cushion 14 is removed from the frame 12 and flipped overwith respect to the view in FIG. 51 to show the face contacting portionsof the cushion 14. The cushion 14 includes a flange 30 that connects tothe mask 12, an inner rim 32 that defines an opening 34 to the innerchamber of the frame 12, and a sealing portion 36 disposed between theflange 30 and the inner rim 32.

Preferably, the cushion 14 is formed of a soft, flexible skin compatiblematerial such as silicone. One suitable material is SILASTIC™, asilicone elastomer manufactured by Dow Corning. It may be molded, by aone shot injection process as known in the art, for example. Differentportions of the cushion 14 may be made with different thicknesses, oreven of different materials to affect stiffness and resiliency forexample. It is also contemplated that the cushion 14 may be made inwhole or in part of foam or gel materials. The cushion 14 may be madebased on a combination of the above processes and materials.

The inner rim 32 and sealing portion 36 are best seen in FIG. 56, whichshows that the sealing portion 36 has a gently curved shape thatprovides a lip that extends beyond the inner rim 32. Preferably, thesealing portion 36 is formed to be more flexible or thinner than theinner rim 32 to conform more easily to the wearer's facial contours. Thesealing portion 36 offers a compliant seal, which can accommodate smallvariations in the shape of the wearer's face and can account for smallmovements of the mask relative to the wearer while maintaining aneffective seal. Depending upon the securing force supplied to the mask10, the cushion 14 may deform to a point where it butts against the rim32. The flange 30 has a rigidity sufficient to withstand usual securingpressures in use of the full-face cushion 14 and tends to retain itsshape and resist deformation. It thus also acts as a supportingstructure.

The embodiment shown herein has a single rim 32 and a single sealingportion 36 thus forming a double walled construction. It is alsopossible to have a single, triple or multiple walled construction.Further, the rim 32 and the sealing portion 36 could be made ofdifferent materials.

If desired, the sealing portion 36 can include a gusset portion that isa gently curved enlarged portion that follows the curvature of the face.

The sealing portion 36 is designed to contact the wearer's face and forma seal therewith so that the gas supplied to the inner chamber of theframe 12 does not leak outside the mask 10. The sealing portion 36includes a nasal section 38 that spans the nasal area, which extendsabove the wearer's nares across the bridge of the nose and is generallyan inverted V-shape as seen in FIGS. 52-54. On each side of the nasalsection 38, side sections 40 extend downwardly to the outside of bothsides of the wearer's mouth, continuing the generally inverted V-shape.A chin section 42 extends between the side sections 40 and is describedin greater detail below.

The profile of the cushion 14 when viewed from above or below has anconcave central portion at the nasal end and the chin end and a convexportion at the cheek portions to fit a wearer's face as seen in FIG. 55.That is, in the plane perpendicular to a wearer's face, the cushion 14is curved to follow the contours of the human face, including theprotruding nose and chin. This is known in the art of respiratory masks.

Referring to FIGS. 53 and 54, the chin section 42 of the cushion 14assumes a shape when viewed from the front and the rear that is notconventional in respiratory masks. As discussed above, in conventionalmasks, the chin section of a cushion is straight or U-shaped in theplane generally parallel to the wearer's face. The conventional idea isto make the chin section conform closely around the mouth. However, inthis embodiment of the invention, the chin section 42 is shaped toclosely conform to the chin's bony contour instead. The bone descriptorfor this region is between the mental protuberance and lower teeth onthe jaw, and it forms an outwardly extending bone line that is curveddownward, much like the shape of a frown. The cushion 14 thereforeincludes the chin region 42 that is shaped like a boomerang or aninverted U and is designed to rest between the lower lip and the mentalprotuberance. As seen in FIG. 54, the shape of the seal may be describedas W-shaped. Any portion of the inverted U or W shape may be adjustableto refine the fit on the wearer. For example, a malleable wire could beformed in the sealing portion to provide such adjustability, by bendingthe wire to conform the sealing portion to the wearer's facial contours.This upwardly curved design or arch is seen in FIGS. 51-54. The sectionrear view may have an arched shape while the front and/or side viewscould still maintain the current shape of the full face mask.

This shape allows the side sections 40 to extend farther downward towardthe lower jaw. If desired, the cushion 14 can be sized to extend to thelower jaw to provide more stable support. By this, the cushion 14 restson the bony regions of the face that are less likely to change shape andcompromise the seal than the softer, fatty regions like the lower lipand cheek.

During treatment, as pressure is applied to the wearer, the lips, whichare flexible, are forced slightly open. The lower lip thus movesoutwardly and slightly downwards. As the lower lip moves as described,an intimate contact with the arch shaped cushion 14 is created,improving the sealing even further, and/or reducing leak through themouth, if desired.

The cushion 14 and mask 10 have been described with reference to CPAP orassisted respiration treatment, however it is to be understood that theinvention generally is applicable to any application where gas and/oratomized liquid is to be supplied to the entrance of the airways. Suchapplications include nebulisers, gas masks and anesthetic machines. Inaddition, the mask can be for use with an oral only mouth mask where themask covers the mouth only. Also, the cushion could extend down beyondthe chin to further stabilize the cushion.

It can thus be appreciated that the aspects of the present inventionhave been fully and effectively accomplished. The foregoing specificembodiments have been provided to illustrate the structural andfunctional principles of the present invention, and are not intended tobe limiting. To the contrary, the present invention is intended toencompass all modifications, alterations and substitutions within thespirit and scope of the detailed description.

What is claimed is:
 1. A cushion for a respiratory mask assembly thatdelivers breathable gas to a patient, the cushion comprising: a non-facecontacting portion connected to a frame; a face-contacting portionstructured to engage the patient's face; and an intermediate portionthat interconnects the non-face contacting portion and theface-contacting portion, the intermediate portion including a gussetportion structured to apply a first component of force to the patient'sface through the face-contacting portion; and a spring structure coupledwith the face-contacting portion, the spring structure being configuredto apply a second component of force to the patient's face through theface-contacting portion, wherein the first and second components offorce to be applied by the gusset portion and spring structure,respectively, determine a contact force to be applied to the patient'sface through the face-contacting portion.
 2. The cushion according toclaim 1, wherein the contact force to be applied to the patient's faceis substantially evenly distributed around the entire perimeter of thecushion.
 3. The cushion according to claim 1, wherein the contact forceto be applied to the patient's face in a nasal bridge region is lessthan the contact force to be applied to the patient's face in cheekregions.
 4. The cushion according to claim 1, wherein the contact forceto be applied to the patient's face by the cushion in a sensitive regionof the face is less than the contact force to be applied to thepatient's face by the cushion in a less sensitive region of the face. 5.The cushion according to claim 1, wherein the intermediate portionextends radially outwardly a distance away from the non-face-contactingand face-contacting portions to provide additional footprint areaoutside a contact line of the cushion.
 6. The cushion according to claim5, wherein the gusset portion has a first side wall extending outwardlyfrom the face-contacting portion, a second side wall extending outwardlyfrom the non-face-contacting portion, and an arcuate wall thatinterconnects the first and second side walls, the first wall, thesecond wall and the arcuate wall of the gusset portion defining theadditional footprint area therebetween.
 7. The cushion according toclaim 6, wherein a distance between the arcuate wall of the gussetportion and the contact line of the cushion defines a dimension that isat least partially determinative of the first component of force to beapplied to the patient's face.
 8. The cushion according to claim 6,wherein the arcuate wall acts as the spring structure to provide thesecond component of force to the patient's face through theface-contacting portion, the arcuate wall having a thickness that isdesigned to allow adjustment of the second component of force.
 9. Thecushion according to claim 1, wherein the gusset portion has a dimensionthat is designed to be variable in different regions of the gussetportion to adjust the first component of force to be applied todifferent regions of the patient's face.
 10. The cushion according toclaim 1, wherein the non-face-contacting portion is removably connectedto the frame.
 11. The cushion according to claim 10, wherein thenon-face-contacting side is removably connected to the frame with acushion clip.
 12. The cushion according to claim 1, wherein theface-contacting portion includes a side wall, a rim extending away fromthe side wall, and a membrane provided to substantially surround therim.
 13. The cushion according to claim 12, wherein the cushion includestwo or more rims and a membrane to substantially surround the two ormore rims.
 14. The cushion according to claim 12, wherein the cushionincludes a rim and two or more membranes to substantially surround therim.
 15. The cushion according to claim 1, wherein the face contactingportion comprises a gel portion.
 16. The cushion according to claim 1,wherein the face-contacting portion has a generally triangular shape.17. The cushion according to claim 1, wherein the gusset portion iscurved to follow the contour of the patient's face.
 18. The cushionaccording to claim 1, wherein the face-contacting portion is designed toapply different contact forces to different regions of the patient'sface at a given mask pressure.
 19. The cushion according to claim 1,wherein the gusset portion is structured to not impinge on the patient'svision.
 20. The cushion according to claim 1, wherein the gusset portionis structured to follow the curvature of the patient's face to reduce aheight profile of the gusset portion.